White Paper: Archival Disc Technology White Paper: Archival Disc Technology 2nd Edition January 2020 White Paper: Archival Disc Technology Content Content ........................................................................................................................................................................... 1 1. Introduction .............................................................................................................................................................. 2 2. Optical Disc Technology ......................................................................................................................................... 4 3. Archival Disc Technology ........................................................................................................................................ 5 3.1 Archival Disc Roadmap ................................................................................................................................... 5 3.2 Disc Structure .................................................................................................................................................. 6 3.3 New Recording Material .................................................................................................................................. 6 3.4 Physical Format ............................................................................................................................................... 7 3.5 Logical Format ................................................................................................................................................. 9 3.6 Signal Quality Measurement ......................................................................................................................... 11 3.7 Specifications for 500 GB AD ........................................................................................................................ 11 4 Long-term Archiving .............................................................................................................................................. 14 4.1 Media Lifetime ............................................................................................................................................... 14 4.2 Disc Tilt and Its Variation in Response to Temperature Changes ................................................................ 15 5 The Future ............................................................................................................................................................. 16 1 Copyright by Sony Corporation and Panasonic Corporation White Paper Archival Disc Technology 1. Introduction Due to widespread network environments and improved computer processing speeds, audio, still images, and video are being produced at an ever-increasing speed, to the point where the American IT research company IDC predicts that the total global volume of data produced and stored will reach 44 ZB (zettabytes; ZB = 1021 Bytes) by the year 2020 (Fig. 1). Recently, IDC also reports that the total global volume of data will grow even further to 163 ZB by the year 2025 (Fig.2). Thus an ever-growing need to archive this burgeoning volume of data for the purposes of compliance, academic research, preservation of cultural assets, and providing new value through data analysis. On the other hand, as data archiving involves a significant cost burden, it can be argued that data centers that handle large volumes of data are faced with a particularly strong need to reduce the cost of storage (initial and operational costs). Optical discs represent a highly promising form of storage media to suit this demand, but in order to truly fulfill the needs of these data centers in future, it will be indispensable to increase disc capacity. Figure 1. Predicted volume of data produced and stored globally in 2020 Source: IDC's Digital Universe, The Digital Universe of Opportunities: Rich Data and the Increasing Value of the Internet of Things, sponsored by EMC (April 2014) Figure 2. Predicted volume of data produced and stored globally Source： IDC’s Data Age 2025 study, sponsored by Seagate (April 2017) 2 Copyright by Sony Corporation and Panasonic Corporation White Paper Archival Disc Technology As data centers choose to archive data on storage media with a short lifespan, investment required to continually migrate this data to upgraded media becomes considerable and ultimately puts a strain on data center’s business. However, optical discs can be used to safely archive data for over 50 years without any need for data migration, allowing data centers to supply their services at lower costs. Many data centers are eliminating air conditioning with the aim of serving as ‘green data centers’ with a low environmental burden and reduced operational costs. Optical discs offer high performance and help satisfy the needs of these ‘green data centers.’ Figure 3 shows the average air temperature and relative humidity in major cities around the world. Optical discs are capable of storing data for over 50 years in any kind of environment represented by the blue shaded area on the diagram. As such, optical discs enable realization of eco-friendly data centers with lower operational costs in any city around the world. Figure 3. Average temperature and relative humidity of major global cities Since optical discs use laser-based, non-contact optical process to write and read data, covering the data recording surface with protective film makes it possible to achieve high environmental durability without any loss of writing or reading performance. Two examples are given below to illustrate environmental durability of optical discs. First is resistance to seawater. Even after an optical disc containing data is immersed in seawater for a period of five weeks, data can be accessed without any problems by simply washing and then drying the disc. Second is resistance to solar storms. Data recording on optical discs does not use electromagnetism, so stored data is entirely unaffected by geomagnetic events. In summary, optical discs are a highly promising form of storage media that meets data center needs, including low environmental burden, low operational costs, and high durability. This White Paper describes the Archival Disc (AD), a new optical disc which achieves greater data capacity in addition to the properties above. 3 Copyright by Sony Corporation and Panasonic Corporation White Paper Archival Disc Technology 2. Optical Disc Technology Optical disc industry is one in which Japan has led the world, evolving as music and video products developed from Compact Disc (CD) to Digital Versatile Disc (DVD) and Blu-ray Disc™. First time a 12-cm optical disc entered the market came with the release of CD on October 1, 1982. CD spread around the world as a handy means of enjoying high-quality music. At that time, basic software for personal computers required tens of floppy disks, but when it could be supplied on a single CD-ROM instead, optical disc quickly became a ubiquitous presence in the IT field. Initial discussions for successor to CD were centered on their usage in AV field, including video information such as movies. But in light of CD market, it was subsequently considered essential that any new optical disc should cover both AV and IT usage, and that capacity therefore be increased to facilitate recording of video content. This led to the creation of DVD, for which laser wavelength was shortened from infrared to red, while numerical aperture (N.A.) of objective was raised to 0.60 to reduce spot size for recording and playback. Meanwhile, mark size and track pitch were reduced to enable high-density recording. With development of single-sided, double-layer discs, maximum capacity was increased to 9 GB. With Blu-ray Disc™, laser wavelength was further shortened to blue-violet and the N.A. of objective was raised to 0.85 to produce a recording capacity that is approximately five-fold that of a DVD. Blu-ray Disc™ recording capacity has now reached a maximum of 200 GB per disc thanks to the use of double-sided, triple-layer discs (Fig. 4). Meanwhile, reduced data bit length has meant that Blu-ray Disc™ is comfortably able to achieve a transfer rate suitable for recording and playback of digital HD video, even at the same revolution speed as a DVD. Figure 4. CD, DVD, Blu-ray Disc™ playback spot and recording mark shapes Process of optical disc evolution from CD to DVD and Blu-ray Disc™ has always allowed backward compatibility—DVD recorders/players are compatible with CD, while Blu-ray Disc™ recorders/players are compatible with CD and DVD—meaning that customers have been able to upgrade to the new standard without any loss of convenience. Panasonic Corporation and Sony Corporation are now able to announce details of Archival Disc (AD) standard developed by the two companies to extend this optical disc evolution into new fields of application and enable stable, high-speed recording and playback of ever-greater volumes of digital data. 4 Copyright by Sony Corporation and Panasonic Corporation White Paper Archival Disc Technology 3. Archival Disc Technology 3.1 Archival Disc Roadmap The roadmap for the AD standard is illustrated in Figure 5. The first-generation, with a recording capacity of 300 GB per disc, was launched to the market in 2015. The second-generation, with a recording capacity of 500 GB per disc, has a target launch after fall 2018. Panasonic and Sony will then utilize mutual